ald1108e Advanced Linear Devices Inc (ALD), ald1108e Datasheet - Page 2

• Manufacturer Part Number: ald1108e
• Description: Quad/dual Epad Precision Matched Pair N-channel Mosfet Array
• Manufacturer: Advanced Linear Devices Inc (ALD)

APPLICATIONS
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BLOCK DIAGRAM
ALD1108E/ALD1110E
BLOCK DIAGRAM
G
N1
Precision PC-based electronic calibration
Automated voltage trimming or setting
Remote voltage or current adjustment of
inaccessible nodes
PCMCIA based instrumentation trimming
Electrically adjusted resistive load
Temperature compensated current sources
and current mirrors
Electrically trimmed/calibrated current
sources
Permanent precision preset voltage level
shifter
Low temperature coefficient voltage and/or
current bias circuits
Multiple preset voltage bias circuits
Multiple channel resistor pull-up or pull-down
circuits
Microprocessor based process control systems
Portable data acquisition systems
Battery operated terminals and instruments
Remote telemetry systems
E-trim gain amplifiers
Low level signal conditioning
Sensor and transducer bias currents
Neural networks
P
N1
(2)
(1)
M 1
G
P
N1
N1
D
(2)
N1
(1)
S
(3)
12
ALD1110E
(4)
M 1
V+(5)
~
D
~
N1
D
V- (4)
(3)
N2
(6)
S
M 2
12
D
(4)
N2
(14)
P
N2
M 2
G
N2
(8)
(7)
P
N2
G
Advanced Linear Devices
N2
(16)
GENERAL DESCRIPTION
ALD1108E/ALD1110E are monolithic quad/dual EPAD ® (Electrically Program-
mable Analog Device) N-channel MOSFETs with electrically adjustable thresh-
old (turn-on) voltage. The ALD1108E/ALD1110E are matched and adjusted (e-
trimmed) at the factory resulting in quad/dual MOSFETs that are highly
matched in threshold voltages and other electrical characteristics. For a given
input voltage, the threshold voltage of a MOSFET device determines its drain on-
current, resulting in an on-resistance characteristic that can be precisely preset
and then controlled by the input voltage very accurately.
Using an ALD1108E/ALD1110E is simple and straight forward. The MOSFETs
function as n-channel MOSFETs except that all the devices have exceptional
matching to each other in electrical characteristics. Since these devices are on
the same monolithic chip, they also exhibit excellent tempco matching charac-
teristics.
These MOSFET devices have very low input currents, and as a result a very
high input impedance (>10
drive many MOSFET inputs with practically no loading effects. Used in
precision current mirror or current multiplier applications, they can be used to
provide a current source over a 100 nA to 3 mA range, and with either a positive,
negative or zero tempco.
Optional EPAD Threshold Voltage Trimming By User
The basic EPAD MOSFET device is a monotonically adjustable device which
means the device can normally be e-trimmed to increase in threshold voltage
and to decrease in drain-on current as a function of a given input bias voltage.
Used as an in-circuit element for trimming or setting a combination of voltage,
current and/or on-resistance characteristics, it can be set up to be e-trimmed
remotely and automatically. Once e-trimmed , the set voltage and current levels
are stored indefinitely inside the device as a nonvolatile stored charge, which
is not affected during normal operation of the device, even when power is turned
off. A given EPAD device can be adjusted many times to continually increase
its threshold voltage. A pair of EPAD devices can also be connected differentially
such that one device is used to adjust a parameter in one direction and the other
device is used to adjust the same parameter in the other direction.
The ALD1108E/ALD1110E can be e-trimmed with an ALD EPAD programmer
to obtain the desired voltage and current levels. Or, they can be e-trimmed as
an active in-system element in a user system, via user designed interface
circuitry. PN1, PN2, etc., are pins required for optional e-trim of respective
MOSFET devices. If unused, these pins are to be connected to V- or ground.
For more information, see Application Note AN1108.
(15)
ALD1108E
V+(13)
V- (5)
~
~
G
N3
P
(10)
N3
(9)
M 3
D
12
N3
Ohm). The gate voltage from a control source can
(11)
S
34
D
(12)
N4
(6)
M 4
P
N4
G
N4
(8)
(7)
2